The optimal treatment of unstable thoracolumbar spine due to trauma, tumors, and tuberculous spondylitis remains controversial. Primary goals in management of thoracolumbar instability are preservation of remaining spinal cord function, restoring spinal alignment, maximizing neurological recovery and early rehabilitation. This can be achieved by optimizing neural decompression, while providing stable internal fixation over the least number of spinal segments [1].

Of the anterior, posterior and combined approaches, it remains debatable which is best [2]. Decompression and stabilization of the thoracolumbar spine can be done through the anterolateral or posterior approach. Posterior stabilization generally requires the instrumentation be placed two levels above and below the site of the injury [34]. The anterolateral and posterior approaches produce favorable results [35] and complications [6]. The main intent of the anterior approach is to enable decompression by corpectomy while allowing reconstruction of the anterior spine [7].

Anterior decompression and reconstruction supplemented with instrumentation is generally believed to be superior to fixation with posterior pedicle screw instrumentation for highly unstable thoracolumbar spine. However, the indications and methods for the anterior approach have not been fully documented [89].

This study evaluated the clinical and radiological results of anterior reconstruction and instrumentation using titanium mesh cages after thoracolumbar corpectomy.

This study included 16 patients: 10 with traumatic thoracolumbar instability (Figs. 3, 4), 3 with tuberculous spondylitis, 2 with metastatic deposits (Fig. 5) and one case with myeloma (Fig. 6). The level was L1 in 6 cases, D12 in 4 cases and L2 in 6 cases. The average extent of canal encroachment was 55% (range, 40%–75%) according to axial CT measurements of the compromised vertebra. The mean preoperative kyphotic deformity was 13 degrees (range, 5–16 degrees). Four patients were neurologically intact, with Frankel grade E on admission. All these patients remained intact postoperatively. Of the six patients with Frankel D on admission, all recovered full motor and sensory functions. Of the six patients with Frankel C on admission, three improved one grade and the other three improved two grades (Table 1). The mean±standard deviation preoperative kyphosis was 2.0±13.5 degrees. The mean kyphosis immediately after surgery was –2.6±14.5 degrees. The mean kyphosis at final follow-up was 3.4±13.5 degrees. There was no significant difference between the postoperative and final kyphosis measurements. The mean height of the involved vertebra before surgery was 41 mm and the mean construct height immediate after surgery and at follow-up was 47 mm and 44 mm, respectively (Figs. 7, 8). No case of severe collapse or signifi-cant recurrence of the deformity was evident. All patients achieved solid fusion with significant neurological im-provement and no significant correction loss. Two pa-tients developed intercostal neuralgia that was improved after intercostal nerve block and medical treatment, postoperative pneumonia (n=1) and superficial wound infection (n=4) (Table 2). There were no intraoperative or late vascular injuries. No case displayed a complication directly attributable to the use of titanium mesh cage.

The vertebral body plays a significant role in maintaining the biomechanical stability of the spine and is responsible for transmitting up to 80% of the axial load applied to the spine [3]. Pathological processes like trauma, maliggnancy and infection can involve the vertebral bodies, resulting in incapability of maintaining anterior column support and stability [28910]. Vertebral body destruction can result in ventral compression of the neural elements and compromise of neurologic stability. In these circumstances, indirect decompression of neural elements through ligamentotaxis alone is not as effective as direct anterior decompression. The patient may need to undergo vertebrectomy and anterior reconstruction [711].

Anterior approaches can achieve sufficient decompression and immediate stabilization of the spinal column [5]. The ideal reconstruction device of anterior column should provide a mechanical stability and spinal alignment maintenance while facilitating stable fusion. The anterolateral approach provides a more direct and complete decompression of the spinal canal. Bone fragments can be removed from the canal under direct vision potentially allowing a better neurological outcome. This approach protects the integrity of the posterior column and is associated with a sustained correction of angular deformity. Disadvantages of anterior surgery include the more extensive approach required, lack of familiarity to many spinal surgeons, the potential for thoracic pain and the potential for pulmonary complications [81213].

The tricortical iliac graft and rib graft have been used extensively to construct corpectomy defects. Disadvantages include a less than ideal shape for corpectomy reconstruction and lack of intrinsic stability. Resorption of the graft during fusion will leads to graft collapse, which creates increased bending moment at the screw-plate interface and can produces fatigue and subsequent failure of the construct [3141516].

The anterior approaches in patients with vertebral fractures requires fixation of only one level rostral and caudal to the fractured vertebral body, whereas in the posterior approach instrumentation may span five or more levels with the the anterion column disrupted with secondary deformity [1718]. The anterior approach facilitates complete removal of the injured vertebral disc, which may prevent chronic post-traumatic back pressure [17].

To optimize fusion, bone grafts are better maintained under compression. This is achieved more effectively using an anterior approach and plating with bicortical screws [1718]. There is little evidence in the literature concerning the efficacy of outcome using the cylinderical mesh titanium cage for postcorpectomy reconstruction. McAfee [6] reported on complications associated with the anterior approach when used in patients with thoracolumbar fractures undergoing decompression and stabilization. The failure rate was 96% (2 of 35 patients).

The primary function of the titanium mesh cage is to provide structural support to the anterior column [1017]. The cage can be filled with an autogenous graft, which also enables maintenance of osteoinductivity and osteoconductivity [2]. The largest endplate is selected to reduce the incidence of subsidence and telescoping of the graft within the vertebral body adjacent to the fracture. With the advent of newer instrumentation techniques and use of anterior approaches, the degree of neurological recovery appears favorable than an earlier report [18].

Multiple cages with varying diameters and heights are available. These can be filled with autogenous bone graft, which also enables maintenance of osteoinductivity and osteoconductivity [1719]. A titanium mesh cage with cancellous bone after corpectomy provides immediate structural support to the anterior column, while the cancellous bone inside the cage promotes fusion. Traditional stability can be achieved with anterior stabilization device. The cages confer resistance to axial compression, lateral flexion and axial rotation. Additional stability can be achieved with an anterior stabilization device.

Spinal metastasis often requires corpectomy through an anterior approach followed by posterior column reconstruction and subsequent instrumentation. This circumferential reconstruction is often associated with significant risks [3132021]. In this study, 2 patients with spinal metastasis underwent preoperative embolization followed by stand -alone anterior column reconstruction with neurological improvement.

The fusion rate in our study was 100%, which is consistent with the literature [671012222324]. Proper fit of the cage and gentle axial loading may create biomechanically— and biologically—favorable conditions for fusion. Bony fusion at the implant-vertebral body interface is sufficient for solid fusion. We have not closely evaluated radiological fusion, but rather accepted radiological stability when the clinical results were acceptable. The radiologic method of fusion assessment is not completely reliable. So, we depended on the fusion mass outside and surrounding the cage to more easily and accurately assess with plain radiography than the fusion within the cage. We filled the bone chips around the cage to help the later assessment. The 1-mm slice CT scans with sagittal reconstruction is superior to plain radiographs for assessment of fusion within and around the cage.

Dvorak et al. [8] recommended anterior and posterior in thoracolumbar vertebral reconstruction to avoid mechanical failure. As a result of biomechanical improvements in anterior instrumentation, several investigators reported good results with anterior decompression and stand alone instrumentation [569192425]. Wang and Liu [26] concluded that the anterior approach or combined anterior and posterior approach is a better option in managing unstable thoracolumbar burst fractures, while the latter should be used only for the burst fracture with a significant posterior column injury.

Verlaan et al. [27] conducted a literature review of 132 papers involving 5,648 patients with thoracic and lumbar fractures treated with posterior, anterior or combined approaches. They concluded that evidence -based guidelines for the treatment of these fractures are lacking and suggested that for a better comparison of surgical techniques, randomized controlled trials are necessary.

Our data agree with these previous studies that suggest titanium mesh cages provide durable biomechanical stability.

This study demonstrates that the titanium mesh cage is effective at maintaining sagittal alignment over a postoperative period of 28 months. The clinical outcomes are compatible with published reports using titanium cages.

Titanium mesh cages with cancellous autograft bone after corpectomy of the thoracolumbar spine provides immediate structural support to the anterior column and offers biomechenical stability without any evidence or any significant recurrence of the deformity. Anterior instrumentation is an effective and safe treatment for thoracolumbar instability, with satisfactory clinical and radiological outcomes.